James Lighthill in reference [1] shows how pressure waves can propagate along a distensible tube. The pressure causes the tube to dilate locally and this reduces the velocity of propagation. The more distensible the tube, the slower is the wave velocity. It is convenient to refer to these waves in the tube as “bulge waves”. Lighthill applies his analysis to blood flow in arteries. This invention, on a much larger scale, applies the same principle to extract energy from ocean waves. A long distensible tube full of water is oriented in the direction of wave propagation and the velocity of the bulge wave inside the tube is more or less equal to the velocity of the ocean waves outside. In this case energy is transferred from the ocean to the bulge wave which grows along the length of the tube. At the end of the tube a piston or other means is used to capture the energy of the bulge wave and generate useful power.
Many prior wave energy inventions use flexible membranes and/or tubes oriented in the direction of wave travel, but none appear to rely on the distensibility of a tube made (or partly made) of an elastic material, as a means of storing wave energy prior to conversion. The novelty of this invention is the use of a tube with elastic walls carrying bulge waves matched to the velocity of the ocean waves.